SkyDemon's pseudo-ILS will not give any output below 500' AGL anyway. I am in full agreement with Chris above.

However, the pseudo-ILS will work for many airfields that do not actually have an ILS, since it operates on runway threshold positions and elevation. It does not rely on terrain data in any way; it is designed purely to guide you to a runway threshold (or to 500' above it, for the vertical component).

In my personal opinion you are trying to coerce SD into something it really doesn't want to be. SD is a VFR flight planning and navigation tool. It is NOT suited for IFR operations and should NEVER be used as an ILS substitute. I know that it is a real temptation to stuff all those gadgets into SD but it simply cannot do the job because it relies on GPS for position and altitude information, its elevation model is too coarse (1 km resolution, I believe) and does not have any radio receiver (ILS, VFR, NDB or otherwise). If you find yourself in IMC with a suddenly disfunctional ILS receiver, you should explore other options to reach terra firma: switch over to a different approach (minima permitting), ask for PAR guidance (if available) or divert to a different airport. Following SD's "ILS" to the ground is dangerous and can get you into serious trouble. Just don't let yourself be fooled by the looks.

Sorry, but I just wanted to get this out for once.

-- Chris.

Is there a means then to recallibrate the GPS reported altitude within SD so that it exactly matches the pressure-set altimeter?

Does SD only offer pseudo ils to airfields that actually have ils approaches or does it work with all?

I dragged the hsi on screen today but at Amazon all airfields it did nothing on android.

Liam

https://www.instagram.com/liam548/

I have just downloaded an APP called Aviation tools for Android. Part of the package is ICAO charts, which show THR elevation and GUND defined as height above WGS84 datum.

Taking LHR 27R these are 78 and GUND 151. Maybe this could account for the discrepancy?

I wonder if tapping the "Alt" prior to the flight where altitude changes to elevation and vice versa could account for the occasional disparity between SD's ILS and the aircraft's? Thanks.

Very Newbytheway

DurhamTeaseAirport

The SkyDemon ILS isn't necessarily designed to agree with any other ILS, it's designed to show you the deflection in degrees from a glideslope that you have configured (default 3 degrees). The setting of the real glideslope, the mismatch between your actual altitude and GPS-reported altitude and the position of the real glideslope antenna are all things that could make them disagree.

Fair enough Tim. Is there any thing we can do to make the Glide Slope in SD agree with the aircraft's Glide Slopes. SD's Localiser is always bang on and agrees with the aeroplanes Localisers.

If there isn't, it may be that we have to make a suitable allowance for the glide slope.

I am sorry to be harping on this point but as you might have guessed I find this a very important useful feature that distinguishes SD from the run-of-the-mill other similar products.

Very Newbytheway

DurhamTeaseAirport

Nothing has changed about our glideslope indication. It simply depicts the diffrence between your angle from current altitude to threshold altitude and the selected glideslope angle, nothing more and nothing less.

Thanks Tim for clarifying the displacement of some Navaids on the VFR charts which I must admit I overlooked, when I compared SD VFR charts to my instrument plates (apples & pears). So thanks for the reminder.

So far as the false fly down indication, I do note also the originator of this post had a similar experience to mine. Is there any thing we can do besides ensuring preflight altitude calibration, in order that we could get the correct indication, noting that I was able to obtain a perfect match between the aeroplanes two glide slope indicators and SD's, previously?

Very Newbytheway

DurhamTeaseAirport